Attitude indicator



July 18, 1950 Filed Feb. 17, 1945 G; c. DRAPER ATTITUDE INDICATOR 6 Sheets-Sheet l G50/QSE C'. DRn/2ER TToR/VEY G. C. DRAPER ATTITUDE INDICATOR July 18, 1950 6 Sheets-Sheet 2 Filed Feb. 1'7, 1945 u M y. a W

F/ci. 4.

/N VENTOR GEORGE C'. /MPER July 18, 1950 G. c. DRAPER ATTITUDE INDICATOR 6 Sheets-Sheet 25 Filed Feb. 17, 1945 //5' IIIIIIIIII HrfoRA/EY July 18, 1950 I G, C, DRAPER 2,515,199

ATTITUDE INDIATOR Filed Feb. 17, 1945 6 Sheets-Sheet 4 July 18, 1950 G. c. DRAPER ATTITUDE INDICATOR.

( 5 Sheets-Sheet 5 Filed Feb. 17, 1945 Fig-n.9.

July 18, 1950 G, C. DRAPER 2,515,199

ATTITUDE INDICATOR Filed Feb. 1'7, 1945 6 Sheets-Sheet 6 FITCH 304 mmcnnue /N VEN To R G50/PQE C'. DRn/2ER rToRA/Ey Patented July 18, 1950 UNITED STATES PATENT OFFICE ATTITUDE INDICATOR George C. Draper, Westmount, Quebec, Canada. Application February 17, 1945, Serial No. 578,533 (o1. :i3-204) t 3 Claims. 1

Introduction This invention relates to instruments for indieating the attitude of a craft or vehicle in relation to a reference plane. More specifically, the invention relates to an attitude indicator for aircraft to enable the pilot to determine the attitude of his aircraft relative to the horizontal plane.

The prior art The type of instrument in current general use for this purpose is based on the principle of indicating to the pilot the relative position of his aircraft to a horizon line which, within limits, remains horizontal. The disadvantage in this type of instrument is that, although the horizon line remains horizontal and it is the aircraft including its other instruments which actually moves, the impression given to the pilot is that the horizon line moves. This apparent movement is in a direction opposite to the actual movement of the aircraft, so that the natural reaction of the Objects Having regard to the foregoing, it is a principal object of the present invention to provide an indicating instrument to the indications of which a pilot will react in the correct sense without conscious mental eifort. Further objects of the invention are to provide an instrument overcoming the disadvantages mentioned above and providing certain positive advantages as will hereafter become apparent.

The invention With these and other objects in view, a preferred embodiment of the invention is constructed as follows. The indicator is a three dimensional replica of an aircraft which is so mounted and actuated that it takes up an attitude in relation to the longitudinal and transverse axes of the aircraft, corresponding to the actual attitude of the aircraft in relation to theA horizontal plane. If the aircraft drops its left wing, the indicator does likewise. If it noses down, the indicator noses down. The construction is such that there is no limit to the movements of the indicator either in pitch or bank.

More specifically, the indicator includes a mounting adapted to be mounted in a craft, withr its longitudinal and transverse axes parallel to.-

those of the craft. A support is mounted for unlimited rotation about the longitudinal axis. The indicator is pivotally mounted on the support for unlimited rotation about theaXis of pitch passing` through the longitudinal axis and at right angles;

to it. The tail and nose of the indicator respectively includes indices. tend above and below the indicator perpendicular to its transverse axis, ythe supporting means including indices substantially the same distanceV from the intersection of the longitudinal axis and the axis of pitch as the nose and tail indices,

There is reference means located close to the indicator positioned to show by the relative position of the indices, the position of the indicator in" pitch.l The indicator is so mounted andv means are provided so that the indicator is visible to the pilot of the craft from his normal piloting position. In one embodiment of the invention, the datum indicia are mounted on a curved trans-'- parent panel close to the indicator and the indices are preferably concentric datum rings re-' ferring to various degrees of pitch.

, More specifically, a preferred embodiment'of' the invention includes an actuating unit mounted. at any convenient place in an aircraft and an.

indicating unit is mounted on the instrument panel. The indicator is mounted in the indicat v ing unit andv its movements are governed by means of self-synchronous motors receiving their impulses from selfsynchronous motors in the acet tuating unit.v In an alternative'preferred embodiment, the actuating and indicating mechaf nisms are combined. In this case, the indicator is on a gyroscopically controlled support and its' movements relative tothe axes of the aircraft are transmitted optically to a screen situated on;

the instrument panel Detailed description Preferredl embodiments of the invention arel illustrated schematically in the accompanying.

drawings, in which:

Figure 1 is a front elevation or pilots View of,

the indicating unit.

Figure 2' is a longitudinal vertical cross sectione Supporting means eX-ly Figure '7 is a transverse vertical crosssection showing, in elevation, parts oftheactuating unit of Figure 5.

Figure 8 is a transverse vertical: crossA section of an alternate form of device showing parts as seen from the rear of the instrument.

Figure 9 is a horizontal cross section showing, in plan, parts of the alternate form lof device shown in'fFigureA 8.

vFigure 10- is a longitudinal verticalV cross section showing, in elevation, parts of the alternate device shown in-'Figure'8- Figures'll and 12 are-wiring diagrams illus` tratingthe method `vof connecting the pitch indicating motorto the pitch actuating motor of the device illustrated in Figures 1 to "1.

` Indicating unit Referring morev particularly to the drawings, Agrepresents the casing or mounting of the indicating vunit AandlBthe casing or mounting of the actuating unit 4of this `particular embodinient ofthe invention. The casing A is preferably of cylindrical form,..suitable for mounting` on theinstrument. panel. ofthe aircraft, and' is provided with. arearwall. I I. Carried centrally ofthe wall I is. the stator of a self-synchronous motorChaving a casing I5 and a centrally arranged shafttl1. On the shaft I1 ismounted, by means'. 0f suitable bearings, therotor 20v of themotor C. The .rotor l Ycarriesa spider bracket,22 on which. is mounted a support, conveniently-,acylinder,25. Extending from the bracket. 22and carriedtherebyis. a bracket 21.

Onthe bracket 21. aremountedbrushes 30 cooperating. with slipringsv 32 mounted onthe stator casingl.

A bracket 35 mountedon.,.the cylinder V25,car`

ries .the casing 31 .of thestatorofanother selfsynchronous motor D. Mounted on the spider bracket 22 is another I.bracketlwhich carries brushes 40 ,cooperating withslip rings 12i on `,an extensionofv the.-,shaft cfthe. rotor 44 ofthe motorD. 'The 'shaft..4.is y.icurnalled bymeans of-ajewel-typebearing ,41 inthe cylinder 25. The shaftAIi .isalso journalledin a suitable bearing.49 in thecasing. `31.

vCarried on theshaft 4.6 .is a `gear wheel 50 meshingwith a gear wheel 52 carried on astub shaft'. .54 having jewelftype .bearings -55 and .53 in.thecyl1nder 25..and.in,a` bracket 50 .respec-l tively, this bracket also; beingY carried: by the .cylinder25. v

The front of the cylinder carries jewel-type bearings 60 andBl in whicheare journalled the ends of shafts 62 and 63 respectively which extend outwards from the wing -tipsof a miniature aircraft E serving as the indicator. The shaft 63 carriesagear wheel meslflng with theigear Wheel 52.

The aircraft in its ,preferred form is a three dimensional replica-cfa conventional craft. For

4 indicating purposes, it carries on its tail an indicating bead or index 10. The bead 13 is preferably of contrasting colour so as to be clearly visible to the pilot at all times. The indicator carries through its pivotal axis a shaft 12, which is perpendicular tc both its transverse and longitudinal axes. The respective ends of the shaft 12 are provided with indicating beads 'Ill and 15 similar to .the .-bead 10. Extending forwardly from the nose of the indicator; is a shaft 10 on the end of which is an indicating bead 11.

The instrument. is provided with a curved transparent front 00 of any suitable material. Thistransparent front carries concentric grad- ,.,uated rings82` to ,be used in conjunction with the yniiningrthev inclination of the indicating aircraft in pitch. .Mounted near the front of the outer casing A is a dial 35 forthe purpose of indicating in conjunction with'- the wing tips of the indicator, the attitudeof. the., aircraft in bank. A background 0r shield 'I9 is attached to the cylinder 25.

Aj conduit 86 shown in' Figure 3 enters'the rear wall I|` of the casing. Wires lead from the selfsynchroncus motors in the actuating unit through the conduit 86 and from here some'wires leadto the stator of motor C, others to the-slip rings 32. From the brushes 30 wires lead, via the bracket 21, the spider 22 and the bracket 39 .toy thebrushes 40. Others lead to the stator of motorDand still'others to the rotcr"20 4of the motor C.

Actuating um't V*The* casing B is xedlymounted in the aircraft at a convenient place and insuch .a wayrthat its longitudinal axis is parallel to thatl of the aircraft. The casing B is preferably cylindrical in form, having a bodyr 90 and ends 9| and 92. The-ends 9| and 02 are removable and secured t'o thev body in anyisuitable manner. These ends are'fprovided -wi'thlbearingsSS and "03. ''These bearings journal the shafts 9'I'and 98v of the outer gimbal ring |00 ofa gyroscope. The outer'gimbal ring |00 is provided with bearings |05 and |06 carrying the ends of the shafts |03 and |00 of the innerl gimbal ring I |02in'wl.1i'ch"theI gyroscope operates. The end' 9|l carries the stator I|5 of a self-synchronous motor H. Mounted on Vthe shaftg91is`the rotor ||6 of the motor H.

Mounted'on the outer gimbal ring |00 is the stator |20 of another self-synchronous motor J, the rotor of which is mounted on the shaft |09 of the inner gimbal ring H0. Carried on the shaft 98 are slip rings |22. -A conduit |25 extends inwardly through the end 92 and from the conduitf |25 extend a number of brushes |28 adapted to cooperate with the'slip rings |22. 'The shaft |08 carries slip rings |30. Extending inwardly from the outer gimbal ring |00 is a conduit |32 carrying a series of brushes |35 adapted tocooperate with the slip rings |30.

From the slip rings |22 suitable wiring V| 23 leads along the outer gimbal ring |00 and through the conduit |32 to the brushes |35. Wiringfnot shown) leads from they slip rings |30 through the inner gimbal ring I|0 to the rotor ||2 0f theA motor J. Other wiring (not shown) leads from the slip'rings |30 to operate the gyroscopc. Other wiring |21 leads to the stator ofthe motor J and wiring |29 leads to the rotor IIB of the motor H. Further wiring (not shown) leads from the-conduit |25 through thecasing/'Bto the stator ||5"of the motor H.

'Electricl system Suitable wiring connects the self-synchronous motors of the actuating unit to the self-synchronous motors of the indicating unit so that the relative movement between the casing B and the outer gimbal ring is reproduced in the motor C of the indicating unit and the relative movement between the outer gimbal ring |00 and the inner gimbal ring ||0 is reproduced in the motor D as will be well understood by one skilled in the art.

The accompanying diagrammatic Figures 1l and 12 showing the wiring between themotor J and the motor D will, from the following, also be understandable.

The line 290-29I in Figure 12 indicates schematcally the point at which the wiring is connected to the slip rings 32 on the casing of motor C.

The rings to which terminals 30| and 302 are connected are each split into two semi-circular segments 3|5 and 3|6 and 3|8 and 3|9 respectively. These are shown in plan View in Figure 11. Two of the brushes of the group 30 are shown at 30a and 30h leading respectively to terminals 303 and 304. The wiring from terminal 30| is connected to segments 3|6 and 3|8. The wiring from terminal 302 is connected to segments 3|5 andl 3|9. The purpose of these connections is to reverse the direction of movement of the rotor 44 when the indicator E passes beyond 90 from the horizontal in bank. A switch 298 (which can be operated manually) is incorporated for the purpose of reversing the wires leading to terminals 309 and 310. At a similar point in the wires leading to the rotor 20 a similar switch (not shown) is inserted. lAs indicated, the circuit in this particular arrangement includes a suitable source of alternating current.

Operation The operation of this form of the device is as follows. The axis of spin of the gyroscope, due to the way it is mounted and operated, always remains vertical. A change of attitude of the aircraft in bank, causes a relative movement between the casing B and the outer gimbal ring |00' and consequently between the rotor and stator of self-synchronous motor H. This relative movement is communicated by the self-synchronous motor H to the self-synchronous motor C and thence to the indicator E. The wiring is such that the direction of bank of the indicator in relation to the transverse axis of the aircraft will be in the same direction as that of the aircraft in respect of the horizontal.

Similarly, when the aircraft changes its attitude in pitch, there is relative movement between the outer gimbal ring |00 and the inner gimbal ring ||0 and this relative movement is communicated to the rotor of the motor D and hence to the indicator E. Again the wiring connections are such that the movement of the indicator E in relation to the longitudinal axis of the large aircraft is in the same sense as the movement of the longitudinal axis of the aircraft to the horizontal.

It will, of course, be understood that amplifying means including the necessary electrical equipment may be used to magnify the impulses from the motors H and J to the motors C and D and otherwise to facilitate the workings of the apparatus, as will be clear to one skilled in the art. It will also be evident that the movement of the indicator need not be exactly proportionateA to that of the aircraft but may be varied throughappropriate electrical and/ or mechanical changes which do not alter the principle involved.

In certain aircraft manuvres, usually only encountered in acrobaties, the direction of movement of the indicator E without the device de` scribed in Figures 11 and 12 would be in the in-A desirablev attitude may be corrected by means of` the switch 298 and the switch reversing the wires leading to rotor 20.

Alternative form The alternative form of device illustrated in Figures 8 to 10 comprises a casing F which carries the various parts of the instrument. casing F includes a recess |50 in which are mounted bearings |55. The bearings |55 journal a shaft |50 on which is mounted a bifurcated gimbal ring or support |60 for a gyroscope. The ring |60 includes bearings |65 for the shafts or trunnions |61 and |68 of an inner gimbal ring |69 carrying a gyroscope. The shaft |68 carries a gear wheel |10 meshing with a gear wheel |13 suitably journalled for rotation on an arm of the ring lliil. The gear wheel |13 meshes with another similarly mounted gear wheel |15.' At

the rear end of the gimbal ring |00 are journalled two shafts |11 and |18 extending outwards from the wing tips of a miniature aircraft G serving as the indicator and which is mounted in such a way that it is normally in an upside down atti-r tude with its tail towards the nose of the aircraft. meshing with the gear wheel |15.

There may be employed, if desired, a bearing to take the weight of the mechanism towards the rear end of the ring |60. In the design illustrated, this bearing comprises gear wheels |89 working between a toothed annulus |90 on the casing and another toothed annulus |93 connected to the rear end of the outer gimbal ring |60. Lights |95 are provided to illuminate the. indicator G. Extending out from one arm 0f the ring |00 is a bracket |80 which carries a shield or background |83.

The rear wall or" the casing is provided with an opening 202. Mounted on the casing in rear of the opening 202 is a reflecting device, as for instance, a prism 204 adapted to reflect the image of the indicator upwards to a prism 205 mounted adjacent the top of the casing F. A pair of lenses 201 and 209 carry the reflected image to a screen 210 preferably of' ground glass or other suitable material, which is mounted on the instrument panel. A casing 2|! houses the lenses and prisms. The screen 2|0 carries concentric rings to be used in conjunction with beads or indices mounted on the indicator G as shown to determine the angle of pitch. The screen also carries a circular scale to be used in conjunction with the image of the wing tips of the indicator for determining the angle of bank so that the image seen by the pilot is substantially as shown inFigure 1 (when the aircraft is in level flight) Operation The operation of this alternative form of the invention is as follows. As in the case of the The' The shaft |11 carries a gear wheel |19 embodiment already Tdescribed, .the .gyroscope in thedrm'er @gimbai ring |69 is -arranged to maintainzits :spinning axis in 'a vertical direction, that is, in a similar sense to the device` previously described. When the-aircraft changes its :attitude infth'e direction of ibank, there is relative movement between thecasing 'F and the outer gimbal ring :E60 and, consequently, relative `movement between :the casing F and the indicator G, -since it carriedzin the arms of the outer gimbal ring I;B.0. Movement of the .aircraft .in pitch causes relative movement 'between the outer gimbal ring lfnnd the inner gimbal ring |69.` This relative movement is rcon'xmunicated to the indicator G through theigear Wheels H0, H3, i15'and H9 so that :its movement in vrelation to -th'e gimbal ring |60 is in the opposite sense to that 'of the inner gimbal ring |69.

When the aircraft is straight and level, thev image .of the `.indicator G is thrown on the screen 2I0`1insuch a way that, to vthe pilot, it appears i-nan upright positionviith the tail towards him. lin-.other words, the image has been inverted in one fsense. Moreover, the wing of the indicator wlh-ichis Jto the vpilotis right, that is, towards the starboard side Voi" the :aircraft will still be on the starboard side 'of the image as seen by the pilot. In'other words, the limage has lnot been inverted in this sense.

Advantages and modifications 'The many advantages provided by the present invention Vwill be apparent from the foregoing description.

YIt is to be understood that forthe purpose of simplicity, conventional vdetails of the various parts of the instruments vshown have been illustrated diagrammatically and in cases omitted. Forinstance, the gyroscopes can be of vconventional types, including the necessary impelling and erecting devices-etc. to enable them tofunction .most .efcient1y,.as will be well understood by one .skilled in .the art. The vself-synchronous motors are lalso of conventional types and of a suitable size for their function. While the description has, for convenience been in terms of aircraft, it is to be understood that the teachings are not so llimited but may be applied to instruments for any craft or vehicle whose attitude it is `desirable to determine from time to, More than -one indicating unit can be.

time. employed so that the attitude ofthe aircraft can be .read .at diierent positions remote from the actuating unit.

It Will be understood that various other modicationsmay .be made in this invention without departing -from the spirit thereof or the scope of the claims, and therefore, the exact forms vshown are .to be taken as illustrative only vand vnot in a limiting sense, it being desired that only vsuch limitations shall be placed thereon as may be imposed by the state of the `priorart or are'set forth in the accompanying claims.

The 'sub-titles used throughout the specification aremerely to simplify reference thereto and should otherwise 'be disregarded.

I 'claimt '1. An vattitude indicator, comprising, a mountingad-apted to bemounted in a craft and having longitudinal and transverse axes parallel'to those of the craft, a support mounted tor unlimited rotation about said longitudinal axis, a three dimensional indicator simulating "aifcraft ".pivotally mounted on vsaid support `for .unlimitedrotation about .aniaxis of pitch, .passing through said :1ongitudinal axis and at right ang-les to .it,.'a, curved transparent front closeto the indicatorfanindex forlthe tail ofthe indicator, anindex forfthe-nose of theindicator, supports extending from the findic'ator above and below .it-iperpendicularito vlits longitudinal fand transverse axes, respectivezindices on said supports, all said indices beingrequidistant from the intersection iofisaid'faxesarrdat such 1a distance from saidiint'ersection 'that .they are adapted to `pass -close to -Saidv liront Ton." movement of said indicator about its transversesaxis.

.'2. .Anvattitude indicator; according to .c1aim`1, wherein 'the i transparent front includes Vconcentric 'datum rin'gsarranged to indicate. various 3degrees' of pitch, the relationship of the indices-itc the rings .'indicatingJt-hefdegree -of pitch ofl'the indicator.

.3. .An attitude indicatorfcomprising', amounting yadapted lto'floe mounted in a craft and having longitudinal and `transverse :axes parallelto V:those ofthe craft, a supportm'ountedifor unlimitedirotation about said longitudinal axis, a three dimensional .ind'icator'simulating .a `craft pivotally mounted on y'said support for unl-imite'di'ota'ti'on about'anaxis of pitch, .passing through said longitudinal :axis .and at right angles to it, Ean .indeifrfor the vtail of .the indicator, .an index for the nose oi .the indicator, fsupportingmeans, vextending from the indicator .above and below Vitfperpendicu'lar to its transverse axis, respective Vindic'z'es on :said supporting means, reference means-'located {close to the indicator and positionedto show by the relative position of the reference means and one or more o'f 'the indices the p'os'itionof the indicator in pitch, said indices beingf-equidistant from the intersection of said axes and at such a distance from said Iintersection that they are adapted to 'pass close to said reference meansbn movement of said indicator about its 'transverse axis.

GEORGE "C. DRAPER.

REFERENCES CITED The following references :are of r'eoord inthe OTHER REFERENCES lSelsyns for Remote Signaling,Y Control and Indication, (published by the General Electric Co., Schenectady, N. Y.; 8 pages; received .Ferial-T6,

1939; Copy in Div. 66, 33-2`04.66) 

